A number of prior patents have disclosed sabre saws having rotatable saw bars and various means for controlling the rotation thereof. For example, Bechtold, U.S. Pat. No. 2,547,922 shows the rotation of a saw bar of a sabre saw about its own axis together with a frictional locking means to hold the saw in position for straight cutting. More recently, U.S. Pat. No. 3,494,490 and 3,494,391, each entitled "Sabre Saw With 360.degree. Swivel Saw Bar" have used a pin locking and a key locking means, respectively, in place of the frictional locking means. U.S. Pat. No. 3,665,983 entitled "Sabre Saws With Angularly Adjustable Swivel Saw Bar" uses a cam actuated spring-biased locking pin, positionable between a locked and an unlocked position carried by the control knob and which, in the locked position, will engage one of the plurality of holes set in the housing a predetermined angular positions corresponding to the desired angular position of the cutting edge of the saw blade.
In each of the last mentioned three patents, the locking and unlocking mechanism is incorporated in the control knob, making the control knob an expensive and complicated assembly. Moreover, necessity to provide room within the control knob for the operating mechanism adds to the overall height of the sabre saw. In Bechtold, as heretofore pointed out, the locking arrangement is not positive but is frictional and could become dislodged because of vibration of the saw in use enabling the saw blade to twist when it is desired to retain it in a set position.
In U.S. Pat. No. 3,729,822 entitled "Sabre Saws With Lockable Swivel Saw Bars" a locking pin slidable on the housing and activated by a trigger slide selectively locks the swivel saw bar against rotation and a spring detent retains the trigger slide and associated pin in either the locked or unlocked position, which at times has been found too difficult to operate and which requires that the saw bar be prealigned before the trigger slide can be moved to the locked position.